The present invention relates to apparatus for measuring the percentage of dissolved gas in a liquid, in general, and to apparatus for rapidly and accurately measuring dissolved gas percentages in liquids moving within a conduit or similar enclosure, in particular.
The presence of dissolved gas in a liquid can produce any number of unwanted conditions in various manufacturing industries. In, for example, the photographic industry, the presence of dissolved gas in a coating fluid can have a decidedly negative impact on a finished photographic product. During the process of coating photographic films, for example, coating fluids are often subjected to pressures well in excess of and well below atmospheric pressure. If the coating fluid contains a significant amount of dissolved gas and this dissolved gas containing liquid is subjected to a low-enough negative pressure, the dissolved gas will come out of solution in the form of gas bubbles. Gas bubbles in a photographic film coating fluid creates voids in the coating fluid that show up as spots or imperfections in a finished photographic print. If the presence of dissolved gas in a photographic film coating fluid can be timely determined, steps can be taken to either remove any resulting gas bubbles or to preferably prevent the occurance of such gas bubbles by subjecting the dissolved gas containing coating fluid to conventional degassing techniques.
Several different techniques are presently available for measuring the percentage of dissolved gas in a liquid. However, each of these techniques suffers from one or more shortcomings that render them either unsuitable, inadequate or less than desirable for the dissolved gas measurement task presented.
In many applications it is desirable to have the percentage of dissolved gas rapidly and continuously measured. However, some gas measurement techniques involve the time-consuming task of extracting a sample of the liquid to be tested and then transporting same to a distant laboratory where the amount of dissolved gas is determined by observing bubble formation in the liquid while the liquid is being subjected to negative and positive pressures. Other techniques either employ apparatus that is not compatible with the liquid to be tested in that it might introduce contaminants into the liquid or are not capable of measuring the type of gas that is dissolved in same. Still other techniques produce unacceptably inaccurate measurements of dissolved gas percentages.
The primary object of the present invention is, therefore, to provide apparatus for rapidly and continuously measuring the percentage of dissolved gas in a liquid moving within a conduit.
Another object of the present invention is to provide apparatus for rapidly and continuously measuring the percentage of dissolved gas in a process liquid with a fairly high degree of accuracy.
A further object of the present invention is to provide a technique for measuring the percentage of dissolved gas in a process liquid that contaminates a minimum quantity of the liquid being measured.
Other objects, features and advantages of the present invention will be readily apparent from the following description of the preferred embodiment thereof taken in conjunction with the accompanying drawings.